Area M
by Andrea O'Down
Summary: The Kraang have managed to create a decent clone of April and mutated New York City and its surrounding area, now called "Area M". After four years of travelling the world and working on a cure with other scientists, Donatello finally comes back. [Alternate Universe]
1. Coming Home

_This story was inspired by an AU-story-idea by my good friend nicollini and an awesome picture of Donatello she drew going with that idea. (If you want to look at it, please check her tumblr. Her username's nicollini.) _

_Thanks a lot for asking me if I want to write the story to your idea, dear! _

* * *

**Chapter 01: Coming Home**

Donatello stood up from his crouching position. He shook off the dust from his coat and readjusted the straps of his messenger bag and his backpack, before he wrapped the scarf tighter around his neck, followed by a quick tap on the goggles he had pushed back on his head to make sure they were still there. And then for the first time since he had entered this area he took a look around. A real look where he could actually see, not only looking for cover and making sure to make no noise and check every now and then that he hadn't been spotted. He was away far enough from the border patrols to not care about being spotted, and he had felt the urge to have a look around for quite some time now. He needed to _see_. Well, as much as someone could see in the darkness, but for Donatello that was enough.

He leaned on his staff, letting his eyes wander over his surroundings, taking in what he could make out.

The area was deserted. There was grass and trees and even a few flowers, but it just didn't feel right. Some of the plants' silhouettes made them look like as if they were from another dimension – which in a way – was true.

With a sigh Donatello allowed his memories of that day take over, the day when the Kraang had terraformed New York city and the surrounding area within a 40 miles radius. That day. _The Day_, how they called it now.

Kurtzman had informed them about a Kraang facility where he had thought they kept another clone of April, and Donatello and his brothers had decided to shut that place down. But when they had entered the facility, ready to blow it sky-high, they had been too late. The Kraang had already set up their machine to terraform the earth, using the clone's DNA to do so. And the moment they had arrived, they had started it.

Donatello could still feel the shock wave knocking him from his feet, he could still remember the silence following the explosion, this deadly silence, and then there had been this fog everywhere, containing these little droplets of mutagen. And after that, everything had sunken into total chaos.

He barely remembered what they had done afterwards, he remembered a fight, though, he remembered the screams of New York's inhabitants, he remembered the burning on his skin from the mutagen fog, but he had no idea what he had been thinking. All he had done had been reacting – getting out of there and back to the lair alive.

It had taken him quite a while to figure out what had happened when they had been back at the lair. He knew now that this last clone of April had been different, different from those they had destroyed at TCRI, but still, it had only been a clone. And that was the reason the mutation of New York City had been unstable. Some people had been turned into mutants, some plants had been mutated, but it still wasn't an environment the Kraang were able to survive in. On the contrary, this fog had killed a lot of them and destroyed their technology, forcing the remaining Kraang to retreat and hide. There had been rumors they were trying to reorganize now, but without their technology, without an ability to contact Dimension X there weren't exactly seen as a threat. Chasing Kraang hadn't been the Turtles' top priority since. They had had more important things to do – like surviving.

After the Day the government had declared New York City and its surrounding region to a prohibited area – first, because they weren't sure how to deal with this epidemic, back when they had thought this had been caused by a virus, and after that when they had been sure that there was nothing to be done, they had sealed it off from the rest of the country because they weren't able to get the situation under control. This was how "Area M" had been set up – "M" as in mutation.

In the insecurity of the first months some rich and/or lucky ones had been able to get out. Donatello ranked himself among neither. If he would have had a choice he would never have left New York. He would have stayed back and fought, keeping the city in an as normal as possible state. But he hadn't have a choice. He had had to leave.

When he had realized there wasn't much he could do and that he was stuck in finding a retromutagen, he had decided to seize the opportunity to be able to join other scientists and work together with them on a retromutagen. So he had contacted some scientists and told them that he had been a scientist himself before he had been turned into a turtle on the Day, but that he had some information on the mutagen. They hadn't asked too many questions about his past, fortunately. Although he would have been able to tell them that all his personal data had been lost during the riots and that he had cared more about saving his data on mutagen. But they hadn't asked about that. They had only been interested in his research on mutagen.

So he had left New York City for what had been planned to be a one-year-leave. But in the end it had been four years. Four long years he had been separated from his family. When the communication technology had still been working in New York they had sent each other messages nearly every day, but then the electricity supply had gotten worse and worse, and in the end it could have taken weeks to hear back from his family. He had sent them a message he was coming home two weeks ago, but he didn't know if they had received it yet. He wasn't even sure if they were still staying at their lair or if they had moved. All he could do now was going to their old lair and hope they were still there.

He looked into the direction where he knew New York City was. Four years ago, before the Day, it would have stood out a mile with its glittering lights in the dark, its illumination as bright as day, the city that never sleeps. But it was dark now, its light a distant dim glowing, pathetic as compared to its brightness of old days.

Donatello had seen satellite pictures. He knew how dark the city was now at nights, what kind of creatures were roaming it in the darkness, what kind of people. New York City, the city that never sleeps, was sleeping now at nights. No, _sleeping_ was wrong. Donatello could imagine the tension among New York's inhabitants when night fell, when all that was important was surviving. No, New York wasn't sleeping. It was wide awake at night, paralyzed by shock.

Donatello took a deep breath. And even now that he knew that, he just hadn't been able to stay away any longer. He and the other scientists had been working on a retromutagen for four years now. And they hadn't been able to find a cure. They had used April's DNA, going through the sequences again and again and again, but it just didn't work. Maybe it was because it hadn't been exactly April's DNA the Kraang had used to mutate Area M, at least that was was Donnie was forcing himself to think. Maybe the answers he needed were waiting inside the city walls.

It was the only thing that made it bearable for him to come back with empty hands because practically, he hadn't failed. He was just still working on it.

The grip around his staff tightened as he straightened up.

"Okay, then," he mumbled as he moved on, "it's time to go home!"

* * *

Michelangelo was searching his way through the sewers' tunnel. He hated it when he was on night duty and the alarm was set off. According to the records it only was a minor problem, so he didn't have to call for his brothers. And most probably it had just been a raccoon or a rat that had set off the alarm. It had been like this the last few times. And never ever would he ask his brothers for backup again if he wasn't sure he really needed their help. He had done that like three times and when it had turned out that it has only been a rat, they had made fun of him. So he wanted to be sure this time.

Fun… They weren't having much of it lately – or in the past four years. He had had to learn how the security system worked and how to read the records. He now was decent at it, but what would he do if he ever had the chance to play video games all night again! But electricity had been short all this time, and they couldn't risk using it for video games or the TV. Their only way of communication was the radio. That was where they got the information from if they needed to wear face masks on a day when they went topside or not, depending on the wind conditions and the pollination from the plants in Central Park.

Central Park had been turned into a jungle on the Day, getting hit by more of the mutagen fog than the rest of the city, a jungle full of mutated plants and mutants of all sorts. And after some time they had realized the pollen of the mutated plants made people mutate slowly, bit by bit. That's why they had to wear face masks from time to time. Most of the people in New York City had a face mask handy, and those who hadn't either tried only to go outside when it was safe or did everything to get a face mask. Michelangelo had seen people fight over face masks.

Actually, he had seen people fighting over all kind of things – clothes, food, fire wood.

He sighed. No, there hadn't been much fun lately. And he was afraid there never would be.

And with that thought he went into stealth mode as he got closer to the place where the alarm had been set off.

And then he stopped, watching closely what was there in the tunnel in front of him, waiting for the right moment to strike. The shadowy figure there obviously was no rat or raccoon, but seemed to be a man, but Michelangelo was sure he could handle this one alone. He darted out of his cover, gaining speed as he ran for the shadowy figure. He practically crashed into it, pressing it against the wall.

He wanted to ask this intruder what he was doing here, the question already waiting on the tip of his tongue, but he didn't have a chance to pronounce it, because at that exact moment the intruder spoke up.

"Hello, Mikey," a voice said, an all too familiar.

Michelangelo drew back a few steps, his eyes widening in surprise.

"Donnie?!" he asked disbelievingly,

"The one and only," the other mutant said and stepped into one of the dim stream of lights falling through the street grate above them. "By the way, what took you? I set off the alarm seven minutes ago. I thought you might have move…oof!"

The last word turned into a gasping sound as his brother wrapped his arms around him and hugged him so tightly that it felt like he was pressing all the air out of Donatello's lungs.

* * *

"Guys, guys, guys!" Mikey called out as he entered the lair. "Guess what I found!"

"Another raccoon, Mikey?" Raphael asked back as he turned away from the practice dummy and faced his brother while Leonardo who had been preparing their dinner in the kitchen entered the living room.

"No!" Mikey gave back and beamed at his brothers. "This!"

And with that he stepped aside and thus revealed Donatello entering the lair.

Leonardo's and Raphael's jaws dropped and their eyes widened.

"Hi, guys!" Donnie greeted them with a wave of his hand.

"I can't believe it!" Leonardo called out and marched over to his brother to hug him. "You're back!"

"Sure am!" Donnie said as he hugged him back with a smile.

When they let go, Donnie found his second oldest brother standing close to him. The hothead hesitated, not sure what he should do now, if hugging his long gone brother would make him lose some coolness points, but then he decided he didn't care and roughly wrapped his arms around his brother. Donnie couldn't help but chuckle silently as he hugged him back.

When Raph let go, he immediately stepped a few steps back.

"Didn't think you'd ever show your face around here again," he mumbled as he eyed up his brothers, the usual grumpy look back on his face as he folded his arms over his chest.

"And still, I'm back," Donnie replied with an insecure shrug.

He took a moment to eye up his brothers. They had changed over the past four years! Michelangelo had grown and thus had left Raphael being the smallest turtle around. But their youngest brother had kept his chubby cheeks which still gave him that childish look.

Raphael seemed to have spent even more for training, his body even more shaped by muscles now.

Leonardo had grown as well and even though he still had well-developed muscles he looked more slender now.

And they all had a more mature look on their faces, their eyes looking earnest and thoughtful, although there could still be some mischief detected in Mikey's eyes, and this somehow relieved Donnie a bit. Although his brothers were grown-up and earnest, but they weren't hopeless.

And then he thought of how he must look like to his brothers in his clothes and luggage, his staff resting in the holder of his backpack. He wasn't even wearing his mask. He still had it, of course – it was in his backpack – but it hadn't fitted the "former human scientist"-appearance he had been going for. Neither had his staff, so he had told people it was just a walking staff. He had lost weight over the last years and hadn't spent not as much time training as his brothers obviously had, so even if he still had some muscles, on the whole he was scrawnier than ever.

"Where's Master Splinter?" he finally asked.

"Master Splinter is out to get some supplies. He won't be back before morning," Leo explained.

"I see," Donnie said. "And April?"

The young woman had moved in with the turtles after the Day. They had decided it would be safer for her if she wouldn't live alone. Her aunt had been out of town on a business trip at the Day. Donnie had checked on her when he had been out of Area M. and she was okay. He had told April via e-mail and it had made this whole situation a bit easier for her now that she knew her aunt was safe.

"She is out to visit her fath...," Leo started, but was cut off by a surprised outcry.

"Donnie?!"

Donnie turned around to set eyes on April standing lair's entrance.

"April!" he greeted as she passed through the turnstiles and ran over to the mutant turtle, wrapping her arms around him.

With a smile Donnie hugged her back.

"You're back," April mumbled as she pressed her face against his plastron.

"I am," Donnie replied.

When April's grip on him loosened a bit, he shoved her at arm's length to be able to have a proper look at her. April had grown a bit, her whole appearance had become more mature, though she was still wearing her trademark outfit composed of her yellow shirt and her jeans shorts. This wasn't the teenager he once had known, this was a woman. And just like his brothers the look on her face had turned more earnest now.

This was what catastrophes did to fun-loving teenagers, Donnie thought – make them grow up fast, maybe too fast.

"How have you been?" he asked April. "And how's your father? Leo said you've visited him."

His eyes had been so fixed on April he hadn't seen that his brothers had gestured at him to stop.

April stiffened and she shot a hurtful look at Leo.

"No, April, I didn't say that!" Leo defended himself. "I was interrupted! I couldn't finish the sentence!"

April looked back at Donnie, tears glistening in her eyes as she shook of his hands and stormed out of the living room.

"April!" Donnie called out and wanted to follow April, but Leo held him back.

"I'm taking care of this," he said and left for April's room.

Donnie looked at his two other brothers helplessly. Mikey had lowered his eyes uneasily, so he turned to Raph, hoping to get some answers. His brother tried to avoid his look for a moment, but then he gave in with a growl.

"Her father died," he said.

"What?!"

"You remember how we put a tracking device on Kirby?"

Donnie nodded. Of course he remembered. It had been his idea, so April could keep better track of her father.

"Well, thanks to that device April had soon found out which places a human turned into a mutant bat preferred. She checked on him every day on the tracking device's records, and even visited his favorite places now and then. He seemed to get used to her again and didn't take flight when she was near. So things were going pretty well," Raph explained. "But about a year ago she realized the tracking device hadn't been moving for a few days. She thought it would have fallen off like it had before. So she went there to get the tracking device back and then look for her father at his favorites places to put it back on on him. She sure wasn't prepared for this." Raph took a deep breath and lowered his eyes. "The tracking device hadn't fallen off. It was right there where it belonged. Her father hadn't moved because he was dead. We got there the same night to salvage the body. We don't know what happened to him, but by the way how battered his body was we think that some mutant haters had caught hold of him."

Donnie lowered his eyes. He had heard of these mutant haters. They made the mutants responsible for what had happened to New York.

"I see," he mumbled.

"She was visiting his grave today," Mikey explained.

With a determined look on his face Donnie left the living room. He needed to check on April.

When he had reached her room, Leo was leaving it.

"Is she better?" Donnie asked. "At least a bit, I mean."

Leo frowned at Donnie. "I guess, but Donnie, I don't think that…"

Donnie didn't let him finish the sentence and entered April's room.

Leo just shook his head. What was it that people kept cutting off his sentences today? And with that he left for the living room again.

* * *

"April?" Donnie asked. He scanned the room and found her cowering on the floor near her bed. She had hugged her knees and was hiding her face. She didn't look up when she spoke.

"Please leave!" she said, her voice still sounding a bit tearful.

Donnie hesitated for moment. He wanted to make her feel better, he wanted to be there for her, especially when he realized her body was shaken by another crying fit. He even took a step into her direction, but then he stopped. He realized that he just couldn't force his comfort on her. That would make everything even worse.

"Okay, if you really want me to, I am leaving," he said then, but he didn't move immediately to give her the chance to hold him back.

"I really..want..you to!" April gasped out.

"Okay," Donnie said again, and then he turned and left her room.

* * *

After telling his brothers that he needed to rest a bit, Donatello entered his room. When he looked around he realized that Master Splinter had kept his word. His sensei had said that his room would always be waiting for him, just like the way he had left it. And yes, his room looked exactly the way he had left it. He wondered how his family had been able to clean it as he realized that his belongings he had left behind back were on their usual places because the room actually looked pretty clean.

He took his staff out of its holder on the backpack and placed it on the floor near his bead, before he put down his messenger bag and the backpack as well. He knelt down and opened the backpack, rummaging it for a moment before he took his mask out. With an earnest look he put it back on carefully. The cloth on his skin felt so familiar, so normal as if he had never taken off his mask in these four years.

With a sigh he slid down on his bed on his carapace and crossed his arms behind his head.

Yes, he was back home. He had waited four years now to be able to think that. Four long years his thoughts had always found their way back here, and finally he had been able to follow them. But why did he feel then as if he didn't belong here anymore?


	2. Welcome Back!

**Chapter 02: Welcome Back!**

When Donnie blinked his eyes open the next morning, he was a bit confused. Where was the sunlight that usually woke him up in the morning and why were the noises reaching his ears so much different from what he was used to? Where was the twittering of birds? Where was the distant sound of cars?

With a frown he sat up, rubbing his forehead. His frown grew even deeper when his fingers touched the fabric of his mask. And then he remembered. He had returned to the lair yesterday. He must have fallen asleep with his mask still on, and now as he looked down his body he realized he was still wearing his coat and scarf. Slowly, because his limbs were still numb he got up and stretched himself. Then he slipped out of his coat and removed his scarf and placed both on his bed. Then he stretched himself once more.

He didn't know why, but somehow he felt uneasy again. Something hindered him from leaving his room, something unnameable, waiting deep down inside him. He just couldn't tell what it was. Fear? Maybe. He had been away for such a long time. It was just natural that he was a bit uneasy being back at the lair. So much had changed. What if he made mistakes? What should he do? Wander around the lair like nothing had happened, chatting with his brothers, doing his work, training? Heck, he didn't even know if they had something planned for today, some mission or so.

Well, there was only one way to find out.

He straightened his shoulders and took a deep breath. And then he walked over to the door of his room and opened it.

* * *

Moments later he entered the kitchen, casually waving at his brothers who were gathered around the table.

"Good morning, guys," he greeted them, earning a chuckle from Mikey in response.

"Morning?" the youngest turtle repeated.

Donnie frowned at him.

"It's already afternoon, Sleeping Beauty!" Raph burst out, chuckling as well.

"Oh, really?" Donnie sheepishly rubbed the back of his neck. "Guess I was really tired. Plus, my biological clock is still attuned to sunlight."

"That's okay," Leo said. "You need to get used to the life here again."

"Thanks for understanding, Leo."

"You're welcome, bro." Leo smiled at his brother. "Have some breakfast, and then Master Splinter wants to see you."

"Master Splinter is back?" Donnie asked surprised.

Leo nodded. "He came back this morning."

"Why didn't you wake me up?"

"Because sensei insisted to let you sleep," Leo gave back. "He's waiting for you in the dojo. Just go to him when you've eaten."

He then turned to his two other brothers. "As for you two, get ready for our patrol. We're leaving in ten minutes."

Raph and Mikey nodded, stood up and left the kitchen. Mikey waved at Donnie with a broad grin.

"Later, Donnie!" he said cheerfully.

Donnie waved back at him, but then lowered his eyes.

Suddenly he felt a hand on his shoulder, Leo's hand.

"Just acclimate yourself," his oldest brother said. "You'll join us on our patrols soon enough."

"Okay," Donnie gave back and forced himself to smile, hoping strongly his brother wouldn't realize it was a fake smile.

If he really had realized, Leo carried it off well. He smiled back at Donnie, gave his shoulder a reassuring squeeze and then turned to leave the kitchen as well.

Donnie waited until Leo was out of earshot and then let out a sigh.

Sure, he had known right from the day he had started his journey back home that he wouldn't acclimate overnight and everything wouldn't be back to normal within minutes. Okay, as normal as it could be, considering the life in New York now, but maybe like the way it had been before he had left. But somehow, it still made him feel sad that everything seemed so normal, yet unfamiliar to him. He knew there was no sunlight or twittering of birds down here, so why had he instinctively waited for that all day? Even after he had realized he was back home, his ears had still tried to pick up the sounds he had grown used to within the last four years.

With another sigh he opened the fridge and took out a bottle of milk. He poured himself a glass.

He carefully took a sip, letting the milk slowly run down his throat.

Well, at least the taste of milk was something he was totally familiar with. The milk tasted just the same here as it did elsewhere. Okay, maybe not one-hundred percent, maybe there was a little tang to it that was different like it probably was with all the things here in Area M. But Donnie couldn't care less. Sometimes ninety-nine percent had to be enough.

He let out a satisfied sigh before he drank the rest of his milk in one gulp.

* * *

Donnie stood at the entrance of the dojo, unsure if he should enter now or maybe wait a little longer. He carefully peeked inside, finding his sensei kneeling in front of their family shrine, his eyes closed, being in deep trance. At least, that was what Donnie had thought.

"Don't you want to come in, Donatello?" Splinter suddenly asked without opening his eyes or moving, and the mutant turtle startled at the sound.

"Hai, sensei!" he replied quickly, surprised by his own words. After all these years he still seemed to be used to reply to his sensei in this way.

As he walked over to his sensei, Splinter stood up and Donnie had a chance to properly look at him. The mutant rat's appearance had changed over the past years. Though Splinter still stood upright and Donnie could somehow sense the strength emanating from his sensei, the ability to stand there completely calm the one moment and put out a deadly strike the next without any hesitation if he had to, but still, something was different about him. There was grey on the top of his snout now, and his beard and his eyebrows seemed somehow scrubbier. And his movements were a bit slower than what Donnie had been used to.

Donatello frowned at this. It had only been four years. Sensei hadn't been old before he had left. He had only been in his forties. Measured in years, he still wasn't old. But why did he seem old now?

_Well, I think the rat DNA is finally showing effect_, Donnie thought sadly.

But when he looked into his sensei's eyes, he realized that at least they were just the same. There was this warm, loving glow in them, and when Splinter spread his arms to hug his second youngest son, Donnie fought hard to blink away the tears that were welling in his eyes.

He flung his arms around his sensei, and when Splinter wrapped his arms around him, Donnie felt safe for the first time that day.

"Welcome back, my son," Splinter said warmly.

"Thank you, sensei," Donnie gave back, giving up his fight against the tears and let them run down his cheeks.

But it felt like something was still missing, and finally Donnie voiced the word he had missed to say in four years now.

"Father," he sobbed.

* * *

After seeing Splinter, Donnie was on his way to his lab. His sensei had asked him barely any questions, just one, to be honest, which in a way had surprised him.

Mikey had practically bombarded him with questions yesterday evening, and so had Raph, and even Leo had asked more questions than was usual for his calm and prudent self. So somehow Donnie had thought sensei would ask him some questions as well. But he was talking about Splinter here, and Splinter wouldn't be Splinter if the one question he had asked had caught Donnie off guard. Sure, he had thought of that question, he had thought of his answer, but he had been afraid of this question all along, so finally being asked exactly this question had startled him.

_Why are you back, Donatello?_

He had stammered something about his family needing him and having missed them, and sensei had accepted it, but Donnie was pretty sure that Splinter knew there was more to it. He just hadn't felt it was the right time to ask Donatello about it.

_Why_ was he back? Was it because he had failed to find a retromutagen? Was it because he hadn't been able to bear it any longer to be separated from his family? Was it because he thought the answers to still find a retromutagen were waiting for him here in Area M?

He wasn't sure. But he knew he needed to find the right words when he was going to tell his family about his failure tonight. They were waiting for answers. But he needed to be prepared. And the best place to think was his lab. When he had been working with other scientists in Washington and New Delhi he had always insisted to have his own lab, his own shelter. And it had helped him many times when he had been stuck.

So what was more obvious than to go to his lab when there was something important he had to think about?

Donnie slid the door to his lab open, expecting to find it like he had left it four years ago, just like his room had been the way he had left it. And so he wasn't prepared to find his lab look completely different.

His eyes widened as he took in the sight of the rearranged furniture, the new gadgets, all the screens blinking, and he couldn't prevent his jaw from dropping.

He didn't even realize the young red-haired woman in the back of the lab who had been checking the readings of the security system on one of the screens, but had turned to face him when he had opened the door.

April frowned at the sight of him. He seemed completely dumbfounded, and even after a few moments he still hadn't moved. So she decided it was time to do something. She carefully approached him.

"Donnie?" she asked gently. "Are you okay?"

The mutant turtle just turned his head into her direction, an undefinable sound escaping his still open mouth, and April wasn't so sure if he actually did see her.

"Donnie?" she asked again, as she moved a little closer.

The look in his eyes changed from something she couldn't quite name, but if she had to decide would go for "distant", and something like recognition appeared in them, as he blinked a few times and then finally closed his mouth with a snap.

"I…I…am fine," he managed to say.

"You sure?" April asked. "You look so…uhm…shocked."

"I guess I _am_ shocked," Donnie replied as he turned his eyes away from April and scanned the lab again. "It has changed!"

"Yeah, we needed to tighten security," April explained. "Your security system was working pretty well, but we had to add one or two things and make sure the new gadgets won't need too much power."

"One or two things?" Donnie repeated as he set eyes on the hammocks and the folding bed in the back of the lab.

April turned her head to follow his gaze.

"Oh, that!" she said. "That's because we turned the lab into our panic room. We can practically seal ourselves off here when we have to. That's why the hammocks and the bed are there. Then there are our stocks of tinned food over there in the cupboard. And back there are the canisters of clean water. Not to forget the flashlights evenly spread in here. So when there is another total blackout, we are prepared."

April tried her best to make her voice sound secure and self-confident, she even put on a smile, although deep inside her, the fear of another total blackout started to build inside her, but April tried to ignore it. She remembered all too well what had happened during the last blackout or rather: what could have happened, but she didn't want to think of that again, so she did her best to continue smiling.

"I see," Donnie replied with a frown, and when he turned to face April again, his frown even deepened as if he had realized the smile on her face wasn't totally true. But he didn't say anything.

They stood there in silence for a while.

"I'm done here anyway," April finally said. "So if you want to have a look around, just go ahead."

And with that she turned to leave the lab, but Donnie's hand on her shoulder held her back.

"April," he said quickly. "I am sorry."

The young woman looked at him, a surprised look on her face.

"About yesterday," Donnie explained. "And…your father."

April turned her head away and lowered her eyes.

"It's okay," she said although Donnie could feel her body wince. Without looking at him she placed her hand on his own, giving it a quick squeeze before she shoved it off her shoulder. "You couldn't have known."

And with that she left the lab. She didn't even look at him when she slid the door closed.

Donnie watched her leave. He fought the urge to just hug her and tell her that everything was going to be alright, but given their situation, the place they lived in, he was sure it would be a lie. He had never lied to April before, and he didn't plan on starting now. He wished so much that he could make her feel better, that he could take her pain away.

But there was nothing he could do except from being there when she needed him, something he hadn't been able to do the past four years. But he would be there now, now and forever – if she let him.

His feelings for April, although they had changed over the years, were still strong. First there had been his crush on her which then had turned into something deeper over time. He had always hoped she would love him back one day, but on his four year-long journey he had realized that April would never see in him what he would like her to see. She saw him as her friend, her brother maybe, but that was all he would ever get.

And although he had tried to avoid this thought at the beginning, he one day had given in and admitted that it was true.

Sure, he still was in love with her and maybe that would never change, but he knew now that being her friend was something he could live with. That wasn't _nothing_. Actually, it was _a lot_, maybe more he could ever hope to get from a woman, but definitely all he would ever get from April. And he had finally accepted it. And after that he had realized that the twinge in his heart whenever he thought of his one-sided love had become less and less intense, until it had turned into something nearly unnoticeable now, and maybe one day it would disappear completely.

With a sigh he turned to his old work table which was now moved a bit more to the back of the lab and sat down on the tabletop.

He could think about April later. Right now, he needed to think of what he was going to tell his family about his return tonight.

* * *

At the evening of the same day they had all gathered in the living room. Splinter, April, Leo, and Raph were seated on the couch while Mikey had preferred to sit down on the floor, his back leaning against April's legs. When he had sat down like that and had looked back over his shoulder to smile at April, the young woman had patted his head gently to show him that it was okay.

But now all their eyes were set on Donnie standing in front of them.

The purple-masked turtle had gone over his little speech again and again in his head, learning every word by heart, but now that he found himself the center of attention, he couldn't help but getting nervous. He felt the urge to close his eyes and let out a deep breath, but he decided against it. He had decided to go for self-confident speaker, and closed eyes and a deep breath wouldn't quite fit this scenario.

"Okay, " he then started, "you all have been wondering why I have returned."

"Not really," Mikey burst out, pointing at Donnie with a broad grin on his face. "You missed us, right?"

"Of course I missed you!" Donnie gave back, mentally rolling his eyes. That was one thing he had forgotten about completely. Speeches never turned out the way they were planned when Mikey was around. "But that's not the reason I've returned."

"Oh." Mikey's grin turned into a sad look as he lowered his eyes.

"I…I mean, not the _only_ reason," Donnie corrected his words quickly which made Mikey look at him with a smile again. "But the main…I mean the _other_ reason is that I and all the other scientists are somehow stuck in finding a retromutagen. We've tried so many things, but all the substances we have been able to come up with, don't work. We onetime thought we had managed to create a stable version of retromutagen, but all it had done was slowing down the mutating process. It still is a start, though, and it will help some people that are in jeopardy of getting mutated due to the pollen from the plants in Central Park, but that was all we managed to produce. One of my co-workers has initiated to produce large amounts of what we call of Retromutagen Attempt Number 468 or '468' for short and send some relief supplies here. But as for a real cure, it has turned out that April's DNA we have been working with and the mutagen that has mutated Area M just don't fit completely, so all our retromutagen attempts have been unstable."

He paused for a moment, looking at his family which Raph took advantage of to speak up.

"Is that a nice way of saying that you've failed?" he asked.

"I am not finished yet!" Donnie gave back angrily.

"But…ouch!"

Raph rubbed the back of his head where Splinter's walking stick had hit him.

"Let your brother finish what he has to say," Splinter said strictly, earning a "Hai, sensei!" from Raph before he turned to Donnie again, beckoning him to continue.

Donnie choked a chuckle. It was good to see that some things would never change.

"I think it has something to do with the fact that the Kraang mutated Area M with the help of one of April's clones," he continued his speech. "And a clone is never one-hundred percent identical with the original. So I think that's the reason why April's DNA didn't work the way we thought it would. And that's the reason why I have returned. I thought that maybe I can find some DNA that will help me create a retromutagen. The chances are thin, I know that. We have no idea what happened to that clone, if it died or left the city, if it still is around here somewhere or if we can find some suitable DNA-samples where the Kraang have started the mutation process, but it is our only chance." Donnie paused for a moment to look at each of his brothers, at April and Splinter. "And I need your help here," he said then.

Leo exchanged looks with the others before he turned to Donnie again.

"You can count on us, Donnie," he said with a determined nod.

"Thank you, guys!" Donnie gave back. "I'll start my work tomorrow. That's all I have for today."

The others got to their feet, Splinter needing a bit more time for that than Donnie had ever seen before which made the mutant turtle frown again. It confirmed what he had thought about his sensei suffering from the effects of the rat DNA.

But when Mikey passed him, his youngest brother stopped, looking at Donnie with a big smile on his face.

"You know what, Donnie?" Mikey said. "I still think you came back because you missed us."

"You know what, Mikey?" Donnie replied with a warm smile. "Maybe you're right."


	3. Old Friends

_Just to clear things up: I decided that the mutation of New York happened after the one-hour special "The Manhattan-Project". So it's canon up to that. ;)_

* * *

**Chapter 03: Old Friends**

"How long do I have to keep this up?" Mikey asked, his voice sounding a bit exhausted from pedaling on the ergometer that had been set up in the living room.

"Just until the battery is fully charged," Leo explained. "We need more power now that Donnie is upgrading our equipment."

"I'm getting tired!" Mikey complained. "When are we going to rotate?"

"In half an hour," Leo replied.

"You said that half an hour ago!"

Mikey pouted, but kept pedaling.

"It's okay, Mikey," Donnie said from inside his lab. "You're almost done."

"Okay," Mikey gave back. "But for the record, I still think that's unfair!"

Donnie couldn't help, but chuckle silently. It was so nice to hear that some things never changed. His brothers – and probably he as well – were still foisting off some of their duties on Mikey when they had the chance, and Mikey, although he kept complaining, did them nonetheless. Although he seemed to complain more often now, which meant that he now got it more often when his brothers tricked him into doing something they were supposed to do themselves.

Three days had passed and as Donnie had promised he had started continuing his work. He actually hadn't reached the real work yet, but that was because he had to make his lab an appropriate workplace again. He needed a properly working computer and stable internet to be able to communicate with his scientist friend in New Delhi. And to set this kind of things up was a challenge here in Area M, a challenge he was sure he could master, but still a challenge, even for him. There were still so many things missing, and he had no idea when he would be able to finally start working on a retromutagen. He first needed his lab back.

This was what had kept him busy the last days.

As for himself he felt a bit better now. He still wasn't sure how he would fit in here after all these years, but at least a few things didn't feel as unfamiliar as they had when he had arrived here.

"Just five more minutes, Mikey!" he called out to his youngest brother.

"You can do it, Mikey!" Leo cheered Mikey on, maybe to make up for the fact that he had been able to duck out of his ergometer-duty today. "Final spurt!"

And then Donnie could hear his brother call out his familiar "Booyakasha!", and it was this moment he finally realized he was back home for good. He bit down his lip hard to prevent himself from bursting into tears.

_Booyakasha…_ He had never been very fond of this word Mikey had made up, but now he realized that he really had missed it all these years.

He took a few deep breaths and blinked away his tears, and when this didn't seem to work he squeezed his eyes shut for a moment, but that didn't work as good as he had thought because one single tear had fought its way out of his eye and was now running down his cheek.

* * *

"I'm sorry, Master," the young man shivering on his knees said, "but they came out of nowhere! We didn't stand a chance!"

"Silence!" the creature at the top of the stairs, sitting on his throne, called out. "Enough of this! I know what they are capable of, but this was the second time you were ambushed and a one week's supply of Shark Tooth had been stolen! You know I tolerate three failures, so you have only one more chance to get this right. If you are defeated one more time, you know what is going to happen to you."

"Yes, Master!" the young man replied, his voice shaking from fear.

"And now away with you!"

The young man stumbled to his feet and hasted out of the hall.

The creature leaned back a bit, his dark features nearly invisible in the dim hall, only lightened up a bit by the moonlight, and he could have hidden here easily, like he had done so many times before when it was time to punish one of his henchmen for disobeying or failing. He loved being one with the darkness, sneaking up on his prey, when they tried to get away, thinking they were fleeing from him, only to realize way too late that they had been running directly into his claws, stumbling backwards when they saw his glowing eyes watching them from nearby.

He chuckled at his memories. It was always so much fun.

He lifted one of his boney hands, examining his claws. It was about time these claws met some flesh again, ripping it to pieces. The sound when claws met flesh was one of his favorite sounds in the world. And now that the mutation had even enhanced his hearing ability, he could enjoy it even more.

He felt a bit of disappointment when he thought that he still had to wait some time until he could punish one of his henchmen. Times were tough, and good followers weren't so easy to find. Sure, you could always have the idiots to follow you, and if you didn't ask too much of them, they were okay, but sometimes you needed people with a brain, a little, at least.

But he knew this young man who had already failed twice. It wouldn't take long until he failed again. He just needed to fight back his blood thirst a little longer.

And with that thought Rahzar got up to his feet. He stretched his slender body, and for the hundredth time he thanked fate for his second mutation. He had hated being Dogpound, but now that he was Rahzar, he couldn't care less about his mutation. He had even accepted this name that stupid turtle in orange had given him. He wasn't sure, why, but he somehow liked the ring of it.

_Rahzar…_ It sounded dangerous, grim, deadly – all the qualities he possessed now.

He stretched one more time and then walked over to the hall's entry. The two Foot ninjas standing there immediately opened the door and let him pass.

_Now_, Rahzar thought, _it's time to visit an old friend._

* * *

Rahzar had just entered the aisle leading to his _old friend's_ room, but he could already hear the laughter.

He rolled his eyes. He really had to think about this lady visitors. It sure was getting annoying.

He knocked at the door extra loudly, and the laughing suddenly stopped.

"Come in!" an angry voice in a Spanish accent said, and Rahzar opened the door and entered the room.

He looked around and then set eyes on the two young women lounging around on the couch together with the mutant that had demanded their attention the whole day now – Xever.

Rahzar gave both the women a stare and they immediately got up, but Xever didn't miss the chance to give them both a slap on the booty before they scampered out of the room.

He waited till they were out of earshot before he turned to Rahzar.

"What do you want, Bradford?" he asked annoyed. "Haven't I just given…" He stopped mid-sentence and gasped for air.

He quickly reached for the bottle of water standing on the coffee table next to the couch, but then angrily chucked it away when he realized it was empty. He slid down from the couch and crawled over to the indoor pool that took up half of the room, dragging his legless body over the floor.

"Been…out of water…for…too long," he panted when he had nearly reached the pool edge. He was just inches away from the water, but it looked like he wouldn't make it, as he slumped down completely.

Rahzar just rolled his eyes and then marched over to the fish mutant and kicked him into the water with an annoyed growl.

Xever hit the water with a splash, but he couldn't care less. He opened his mouth wide as soon as he was under water taking what would be called a deep breath if he wouldn't have been under water.

When he broke the surface again and swam over to the pool edge, he let out a sigh.

"Now, that's better," he mumbled.

"Wouldn't it be easier for you to stay in there all the time?" Rahzar asked.

"Sure," Xever gave back with a shrug. "But the ladies prefer the couch since you refuse to get this pool heated."

"I am already granting you more than enough privileges if you keep in mind that you can't walk nor fight," the dog mutant grumbled. "You're lucky you are of some use for me."

"No, you _need_ me," Xever gave back. "Big difference. So you better keep me entertained as long as you need my precious venom to make your fancy little drugs."

"I can always seal you away in a water basin and only get you out to milk the venom out of you whenever I need it," Rahzar said in a warning voice. "I just need you to be _alive_, I don't need you to be _happy_."

Xever chuckled. "Can you guarantee that my venom will be as good as it is now if I am just alive and not happy?"

Rahzar answered with a snarl.

"See?" Xever smirked. "Then you better keep me entertained. And now tell me, Bradford, what do you need?"

"Venom, of course!" Rahzar burst out. "This week's shipment had been stolen!"

"Yeah, I thought so," Xever said matter-of-factly as he looked down on his one hand and examined his fingers before he gazed at Rahzar again, his eyes glistening warningly. "And this is why you have to keep me entertained."

* * *

"What's this all about, Leo?" Donnie asked as he followed the Turtles' leader through the sewers' tunnels.

"You'll see," Leo gave back and led Donnie into one tunnel before he stopped in front of an iron door.

Leo pulled out a key that had been tucked under his belt and unlocked the door. The heavy door creaked loudly as it was pushed open. Leo reached for the light switch next to the door.

Donnie frowned as the lights went on with a flicker and followed Leo inside.

"We think the subway personnel used this to lock away their expensive equipment, but it was empty when we found this room," Leo explained. "They probably took it to sell it, back when money was worth something."

"Okay." Donnie looked around the room, letting his eyes wander over all the boxes that had been stashed in there. He walked over to one of the boxes, knelt down in front of it and opened it, his frown even deepening as he looked at the pills, packed in little plastic bags, the box contained. "What is this stuff?"

"It's called 'Shark Tooth'," Leo said. "A drug the Foot and Purple Dragons use to keep their supremacy on the streets. Whenever we get knowledge of a new shipment we try to catch it. We were successful yesterday." Leo sighed. "The more of this witches' brew is withdrawn from circulation, the better."

"What are they made of?" Donnie asked as he took one of the little plastic bags to examine the pills.

"We don't know," Leo replied. "April wanted to analyze it back when we had no power failures and all of the equipment in your lab was still working, but as you know this didn't last long, and we were pretty busy back then. And April isn't you. She did great on the security system and she still is getting better, but she is no scientist." Leo shrugged. "Hope that doesn't sound unfair. We really owe her a lot."

"I won't tell her, no worries," Donnie gave back. "And once my lab is back in its old state and I've been able to set up a working electricity network with the shipment of equipment from my friend from New Delhi, I'll try to analyze this stuff. Maybe we can use some of its ingredients for medicine or something like that."

Leo nodded. "That's what I had in mind." But then he frowned. "You sure your friend can send you the promised equipment?"

"I hope so," Donnie replied with a shrug. "In the meantime we have to use the ergometer."

"You mean _Mikey_ has to use it, right?" Leo grinned.

Donnie chuckled. "You and Raph can't stop letting Mikey do your chores, right?"

Leo laughed. "Well, some things never change."

"True," Donnie gave back. "And I'm glad about it."

"Yeah," Leo said with a smile. "Me too."

They were silent for a few moments, but then Leo spoke up again, "We better get back now. We await Casey for his monthly visit today or tomorrow, and I don't want to miss him when he arrives."

Donnie just nodded as he got back to his feet.

Casey had moved to the surrounding area of the city some months after the Day together with his father and his little sister, because it was a little less dangerous out there. From what his brothers had told him in e-mails, Casey and his family had set up a farm and were now raising crops. Surprisingly for all of them, the surrounding area had turned out to be fertile and the crops eatable. Some people had farms now, coming to the city now and then and trading food for other useful things. And of what Donnie had learnt today these drugs seemed to be one medium of exchange. He choked a sigh as he followed Leo back to the lair. This city had changed so much. But what had he been expecting? This wasn't New York any longer. It was Area M.

* * *

They had just entered the lair, when they heard a voice behind them.

"Now, look at that," someone who sounded really familiar to Donnie said. "If that isn't my old friend Donatello! Now, that's what I call a welcoming committee!"

Donnie turned around and set eyes on Casey Jones. He quickly scanned the young man he once had a lot of problems with. But after the incident with the Kraathatrogons, the alien worms from Dimension X, they had buried the hatchet, and had gotten along pretty well from then on. And it somehow had made him feel a little bit better when he had heard that Casey and his family now lived in a place where it was a bit safer than in New York.

For some time Donnie had even hoped his brothers, his sensei, and April would follow Casey's lead and move to the surrounding area as well, but he had soon realized that this had been vain hope. His brothers would never leave the city. They somehow felt responsible for what had happened to the city, and they now had this mission to perform damage control, at least a bit.

He wandered over to Casey, eyeing him up. Casey's face was weather-beaten, but he still was as lanky as Donnie remembered him. Casey had a really big backpack on his back, but his outfit was the same he had worn years ago, although it seemed well-worn now. And Donnie had to choke a chuckle when he saw that Casey still had his hockey stick with him which was now attached to his backpack. Only Casey's mask was missing which was a bit unusual, but Donnie didn't really care when Casey opened his arms and the two hugged.

"Good to see you're okay, Donnie," Casey said.

"Same," Donnie gave back with a smile.

When they let go of each other, Leo walked over to Casey to give him a welcome hug as well.

When they were done, Leo turned into the direction of the aisle that led to the dojo and their rooms and called for his brothers.

"Guys! Casey is here!"

There was a rumbling to be heard and moments later Raph darted into the room!

"Casey!" he called out.

"Raph!" Casey gave back, opening his arms, but Raph had so much speed and literally crashed into Casey, tackling his friend to the ground.

"Ouch!" Casey uttered, but then they both started laughing and Raph got back to his feet.

But Casey couldn't get up because the weight of his backpack kept him on the ground.

"Geez, like a turtle on its back," Casey said as he tried to get to his feet, struggling while doing so.

Raph just rolled his eyes as he held out his hand. Casey seized it and let Raph help him to his feet. The mutant looked at him with a furrowed brow.

"What?" Casey asked, but then laughed insecurely. "Oh, yeah, sure. No offense!"

"None taken," Raph gave back with a grin as he patted his human friend on the shoulder.

"Caaaaaaaaaaaaaaaaaaaaaseeeeeeeeeeeeeeeeeeeeey!" Mikey shouted when he entered the living room in the same moment Casey was back on his feet. Raph jumped to the side just in time before it was Mikey's turn to crash into Casey and tackle him to the ground.

Casey just laughed and hugged Mikey back as the youngest turtle flung his arms around his neck.

"You guys are making this a habit, right?" Casey asked when Mikey helped him up. "You're lucky I didn't bring eggs!"

He looked over to the aisle that led to the dojo where Splinter and April were standing. The mutant rat gave Casey a welcoming nod, and Casey nodded in return, but then Splinter turned around and went back to the dojo. Casey still was a bit afraid of rats, although it has gotten much better, but he and Splinter had agreed on not pushing Casey's luck.

But then he looked at April. The young woman returned his look with a smile and then went over to him. They hugged, and Donnie couldn't help, but lower his eyes. After all this time he still couldn't watch them hug. When he heard them move again he looked back up at them.

They looked into each other's eyes for a moment and April gently touched Casey's arm which gave Donnie's heart a twinge.

_You'll never learn, Donnie, huh?_, the mutant turtle thought, mentally slapping himself for still feeling hurt when April and Casey hugged. Why couldn't he just let this matter go?

But his thoughts were interrupted when Casey spoke up.

"Now, let's see what I have in my little backpack for you, shall we?" Casey said to the others.

"Did you bring pizza?" Mikey asked immediately.

"Mikey, you know there aren't any pizza trees on my farm, don't you?"

"Why not?"

"Because pizza trees don't exist."

"Why not?"

Casey just sighed as he placed a hand on Mikey's shoulder, guiding him to the kitchen. "But let's see if we can whip up something pizza-like from what I have in my backpack."

"Yay!" Mikey called out gleefully as he punched the air.


	4. A Kunoichi's Life

_Thank you all for your feedback! ^^_

_BubblyShell22 was confused that Fishface needed to be in the pool, although he has a breathing apparatus on him. Well, actually, just like his robotic legs, his breathing apparatus isn't working any longer. That's why he has to stay close to the water._

_As for thegirlwholived's suggestions of doing a chapter in April's point of view, there is more April in this chapter. And a lot of Karai, for that matter. ;) _

* * *

**Chapter 04: A Kunoichi's Life**

"_Your time as a leader is over, Karai," Rahzar said, the amusement clearly hearable in his voice as the kunoichi, whose hands he was holding in a tight grip above her head, kept struggling and trying to kick him although they both knew it was of no use. "It's time for you to step down."_

"_You gotta kill me first!" Karai spat. _

_Rahzar chuckled. "I was so hoping you were gonna say that!"_

_And with that his free hand moved to her armor, tearing the metal plates apart as if they were made of papier-mâché until the bits of her armor landed on the ground with a clank._

_And then he moved his hand back to her body, his claws moving over the black fabric of her jumpsuit almost gently, before he let his claws sink into the fabric, slowing pushing them deeper until they were slowly digging into the flesh of her body._

Karai awoke with a start. Her one hand immediately moved to her belly where she could still feel the ridged, ugly scars under the fabric of her long-sleeved nightshirt.

In an attempt to calm down her pounding heart she looked around the room, trying to confess herself that this had just been a nightmare. Again.

Karai looked over to the window and realized it was dawning anyway. She could just as well get up then. This was in any case better than trying to fall asleep again and take the risk of having another nightmare.

And with that thought she pushed the blankets aside, got up and scuffled to the bathroom. Her hand moved to the faucet. If she was lucky, today, there would be water. She turned it on, and with a gurgling sound the water started running.

Karai smiled before she splashed her face with a few handfuls of water. At least a little bit of luck seemed to come her way. Better than nothing.

She then lifted her head, dried her face with the sleeve of her nightshirt and went back into the main room after that. For a moment she thought about turning on the lights in the living room, but then she decided to better not push her luck. So she went over to the window and pulled the curtains aside. It was still this slight morning light before sunrise which made everything look so pale. She opened the window and took a deep breath of fresh air. Well, as fresh as the air could be here in Area M. And wearing no face mask was okay at this early hour, although Karai remembered that there hadn't been any warnings about mutated pollination today. So this was the freshest air Area M had to offer.

Karai took another deep breath and then walked over to her bedside table and got a little pocket mirror out of the drawer together with a little piece of black eyeliner. This eyeliner was the only piece of make-up she had been able to keep over all these years. No-one really cared about proper make-up here. But for someone who had really loved her make-up she had at least tried to keep a little bit of it up. And when she had found this piece of eyeliner on the streets it really had made her day.

So she sat down on the floor and looked into the mirror. The mirror showed her a pale, thin face. Her hair had grown longer now and was falling down her back to her shoulder blades. And it was all black. Dying the hair at the back of her head blonde had become too difficult in Area M, because hair dye had become really, really short. So she had dropped it one day. Nothing was left from the fancy haircut she had worn four years ago. But she still had bangs, but now cut them herself with the kitchen scissors when she had the feeling they had grown too long. And she kept the strands before her ears the same length they had been when she had still worn her hair short. So this was the closest she could look now to what she had looked four years ago. Well, except for one.

She moved the kajal to her one eye and encircled it with black, then the other as well, and then she examined the result in the mirror again.

For a moment an image of the old Karai flashed in the mirror, the Karai with the stunning make-up and the awesome haircut.

With a sigh Karai squeezed her eyes shut for a moment and then looked into the mirror again that now showed her real face.

A slight smile appeared on her face when she did so. Well, _this_ was the closest she could look to the Karai from four years ago, and it was something she could live with.

* * *

It was afternoon when Karai left the apartment building, wearing jeans, a black longsleeve, boots, and a leather jacket that was at least three sizes too big, but who cared? Clothes had to keep you warm, not make you look beautiful here in Area M.

Karai turned into a side street and entered a run-down, stuffy pub, the cigarette smoke blowing into her direction when she opened the door took her breath away for a moment, but she recovered almost immediately and went over to the counter. She climbed a bar chair and looked at the bulky bartender.

"The usual, Harmony?" the bartender asked, and Karai answered with a nod.

"Do I need to ask you if you can pay?" he asked with a raised brow, and Karai took a white pill out of her pocket and shoved it over to him. It was one of these Shark Tooth-pills Karai had mugged from one Purple Dragon-dealer two days ago. In consideration of how many of these pills the Purple Dragon had had with him, she would be flush for the next days, but this didn't mean she would sit around lazily. She would need a new job sooner or later, if not for the payment, then for killing time.

So when the bartender placed her glass of booze in front of her, Karai took a quick sip and turned to him again.

"You got anything you want Mr. S to know, Frank?" she asked.

Frank leaned forward a bit and lowered his voice.

"Well, I _heard_ that Gonzales has problems with one of his junk dealers," Frank explained. "It's the one with the 'Second Chance'-shop. I _heard_ he refuses to pay his dues and that Gonzales would pay if _someone_ taught that guy a lesson."

"And what kind of lesson have you heard he has in mind?" Karai asked matter-of-factly. "One where he could still pay his dues or something more _permanent_?"

"I heard Gonzales would like to settle for the still paying-option."

Karai nodded. "I'll see what Mr. S says to this little story of yours," she said. "And if he agrees you might hear an interesting story of what has happened to that junk dealer tomorrow."

"You have an idea what Mr. S would do to him?"

Karai shrugged. "You know, Mr. S and I have this division of work," she explained and downed the rest of her drink in one gulp. "I do the legwork, he does the dirty work."

"This guy sure is a mystery," Frank declared. "No-one has ever seen him, even those of his victims who are still alive can't tell anything about him. If he wouldn't do such awesome work, I would doubt he exists."

Karai looked at the bartender with a smirk. "Well, you know, Frank," she said as she got up from the bar chair, "'S' could stand for shadow."

"And no-one knows for sure, huh?" Frank asked.

Karai shrugged. "I guess." And with that she left the pub.

* * *

At the same time another kunoichi was sitting on her bed and reading a book. They had a free afternoon and she had finished checking the security system readings half an hour ago.

Raph, Leo, and Mikey had left to help Casey with selling his groceries. Times were tough in Area M, and getting mugged was an all-time-possibility, especially when you had food with you. So having three ninja turtles as your bodyguards wasn't a bad idea.

They had asked April to join them as well, but after the party that usually followed Casey's arrival when they had finished dinner with the food he had brought, April was glad to have a little peace and quiet.

She knew that Donnie was in the dojo right now, together with Splinter, catching up on his training. The purple-masked turtle refused to let anyone else than Splinter see how much he had rusted over the years. He still was a deadly, highly trained ninja. After all, he _had trained_ in the past years. He just wasn't in as good shape as his brothers were. And April knew this was embarrassing for him.

Under normal circumstances she would have comforted him, but things were a bit tense between them. She still wasn't sure where that anger deep inside her whenever he was near really came from, and she sure didn't want to find out. She just hoped it would fade away the more she got used to having Donnie around again. But for now, she needed a bit distance.

It was that moment when there was a silent knock on her door, and after she had asked him in, the door opened and Donnie popped his head in.

_Speaking of distance…_

"Sorry to bother you, April," he said quickly, his voice sounding a bit uneasy. "But I can't find my old toolbox, and Leo told me you were in charge of keeping my lab in order, so do you know where it could be?"

"Sure, Donnie," she gave back. "It's in the drawer in the back of the lab where we keep all the other stuff we don't use on a regular basis."

"Ah, okay, thanks, April!"

"You're welcome!"

But before Donnie left he quickly glanced around April's room, something he hadn't been able to do when he had tried to comfort her when she had been crying after his arrival, and a deep frown appeared on his face when he saw Casey's old hockey mask on the wall next to April's bookshelf.

Why did April have Casey's hockey mask? Hadn't Casey lost it? Okay, that was something he had made up in his mind, that Casey had lost his mask. It had been the most logical explanation to him. But seeing it here in April's room in one piece sure messed up his neat theory.

"Something else I can help you with, Donnie?" April looked at him with a raised brow.

"No, no, everything's fine!" Donnie gave back. "Thanks again!" And with that he quickly closed the door behind him.

April had seen the confusion in his eyes, but wasn't sure what could have caused that. It must have something to do with her weird behavior towards him, and it was moments like this that she hoped she knew for sure why she was angry at him and that things between them could be back to normal.

But she _was_ angry at him. She did her best to hide it, and sometimes the relief and happiness that Donnie was back in once piece was outshining her anger, but there were times when her anger got the best of her.

Was she angry because he came back without a cure? No, that couldn't be the reason. She had always known that the chances of finding a cure had been thin, even with Donnie's knowledge and dedication.

No, it was something else. And she sure had been glad when she had seen him at the lair at the day of his arrival. But when he had mentioned her father, it had felt like her world had crumbled to pieces again.

_Her father…_

An image of her father before his mutation, her real father, the father she had been able to talk to and to hug, appeared before her inner eye, but quickly was replaced by an image of his mutant form. And then she saw him lying on the ground again, motionless, covered in blood.

But before her mind could go any deeper into what she had experienced back then, she fiercely shook her head, thus fighting these saddening images into the back of her mind again. At least for now.

* * *

In the meantime Karai had arrived back home. She was kneeling in front of her bed and removing some of the floor plates. When she was done she retrieved a box from the void underneath and placed it on the bed. She put the floor plates back in place and then sat on her bed, opening the box and spreading its content on her bed. There was a black jumpsuit, black boots, several knives, black gloves, and a sword.

When she held the sword in her hands, she hesitated. It was a shikomizue, closely resembling the one she had owned four years ago. She slowly unsheathed it and watched how the light was reflected on its blade.

_Four years…_

She had been going through a lot in this time, and her original plan had been to keep a low profile, live as normal a life as was possible in Area M, and so she had chosen the name 'Harmony' and pretended to be a normal young woman that had to fight through her day like all the others did in Area M. A young woman, though, that could deal out blows when she had to, but nothing more. No ninjitsu, no being a kunoichi, no lurking in the shadows. Just getting through the day and waiting till it was time for her revenge.

But it had turned that to take revenge you needed money. And it had also turned out that after all these years of being a kunoichi, of learning the art of ninjitsu, it had been simply impossible for her to get the kunoichi out of her completely.

That was the reason why she had decided to be Harmony during the day and Karai at nights. Well, not really Karai, but Mr. S, a cover name she had made up, so her enemies would never find out Mr. S really was a woman. No-one had ever seen Mr. S before. Those she was sent out to kill would never be able to tell anyone who she really was, and those who she just needed to teach a lesson, never caught a glimpse of her. She attacked them from the shadows, from behind, injured as much as it was necessary to get her employer what he wanted.

Ambush them, attack them, disappear – all in the blink of an eye. This was the usual proceeding. But sometimes she needed a bit more fun. She then attacked them from behind pulled a paper bag over their head and bound them, and thus have more time to have some fun. Her knowledge on killing and torture methods sure had increased in the past years – on the one hand due to the fact that weapons were short in Are M and if you wanted to do a good job, you needed to be creative sometimes, and on the other hand she really enjoyed it.

And she always left a card when she was done with her victim.

The card told them what they were supposed to do – and who had hit them. Well, when she was supposed to keep them alive. For the others, it just said who had killed them. This card had become Mr. S' trademark. And it had always worked. No-one knew who Mr. S was, no-one knew Harmony actually was a highly trained kunoichi. This was Karai's plan of surviving. And it had turned out pretty well so far. Soon she would have her revenge.

_But first_, she thought as she sheathed the sword again and put it down on the sheets, _it's time for Mr. S to strike again. Tonight._

* * *

April was still in her room reading her book when there was another knock on her door. She rolled her eyes. Couldn't she spend one afternoon alone?

"Come in!" she called out, but when Casey popped his head in, she was a bit surprised. She had expected that it was Donnie or Mikey.

"Oh, hi, Casey," she greeted him.

"Hi, April," the young man gave back. "Leo asked me to tell you that dinner's ready in twenty minutes."

"Ah, okay," April gave back. "Thanks, Casey."

"You're welcome." He hesitated a bit but then entered her room.

He pointed at his mask on the wall. "You still keep that, huh?"

April followed his gaze.

"Well, of course," she said. "It was a gift."

"A gift to remember me, yes," Casey clarified. He went over to her room and sat down on the edge of her bed.

"April," he started hesitantly. "My offer from four years ago still stands. And I still think it would be best that you live with me and my family." April raised a brow. "I don't have any expectations on you!" Casey added quickly. "It just would be safer, you know."

"Casey," April said. "You know that I can't do that."

"Why not?" Casey gave back, his voice sounding a bit angry. "I got it that you didn't want to come with me four years ago because of your father. But he is gone for a while now. I gave you time to mourn, but now you should face the truth. It is safer for you to stay with me and my family."

April squeezed her eyes shut for a moment when Casey mentioned her father, but then she looked at him again and slowly shook her head.

"Casey, I can't," she said. "My place is here. With my family."

Casey lowered his eyes for a moment.

"And what are you and me?" he mumbled.

"We're friends," April replied. "You know that."

Casey nodded, his lips pressed into a thin line. He took a deep breath before he spoke up again.

"You know, there was a time when I thought we were more than that," he said.

"Yes, Casey," April gave back, her voice soundless. "Me too."

* * *

That night Karai stood in front of a shaking old man lying on the dirty ground of a side street, her head covered by a black shawl. Only her eyes were visible. She had pulled a paper bag over the man's head to block his view and his hands were tied. He was breathing heavily, afraid that his last hour has come.

Karai placed a paper card on his chest and then cut his bonds with a knife, and the next moment she had disappeared.

She was making her way over the roof-tops, self-satisfied with what she had achieved tonight. She had no idea why she had decided for the paper bag tonight, but it sure had been fun. And it felt like she had needed that tonight. Yes, sometimes it was great to be a kunoichi.


	5. Invisible Walls

**Chapter 05: Invisible Walls**

It was late at night, but Donatello was still awake, sitting at his work desk in the dimly lit lab. He was waiting for a message from his scientist friend in New Delhi. And because he had to stay up anyway, he had volunteered for the night shift.

There wasn't much else he could do than either wait for the alarm to go off or the well-known _beep_ when he had received a message. And due to the recent electricity shortcuts, they had had to use most of it for the security system, but Donnie had insisted that they had to keep up the laptop and the router, so he wouldn't miss his friend's message. Whenever he got what he needed to make their own electricity system, everything would be easier. It was a lot better now than a week ago when he had arrived, but still not as good as he had meant it to be. He needed this shipment his friend had promised him so that he could work at nights as well. At the moment, they just made sure they had enough electricity to keep the security system working overnight and went from there in the morning.

So in lack of something else to do, Donnie let his thoughts wander like he had done so many times the past days. There were still so many things he couldn't understand. April was acting so distant, and he had no clue why. Neither had he an idea of what to do now.

At least his brothers didn't seem to have changed more than what would be understandably under the given circumstances. Mikey was still the cheerful one, Raph the grumpy one, and Leo the reasonable one. And they still treated him like their brother and made him feel welcome here. And the same went for Splinter.

_Splinter…_

Donnie still couldn't believe how much his father had aged. He now was pretty sure that it had something to do with the rat DNA, and he had spent several hours thinking of what he could do to stop this process. Well, there was Retromutagen Attempt Number 468 that slowed down the mutation process. And that was the other reason he was awaiting for this shipment so impatiently – it would include relief supplies of 468.

He wasn't sure, if it would help Splinter, though. Splinter's mutation had been caused by another strain of mutagen than the Kraang had used to mutate New York City. And there was nearly nothing left of the old mutagen anywhere. But if the Kraang had stashed old mutagen anywhere, it most certainly would be New York City. So if 468 wouldn't work for his sensei, Donnie would have to add "Find supplies of old mutagen" to his To do-list, together with "Find DNA of April's clone". To save New York City, he would need the DNA of April's clone, but to save his father, he might need old mutagen. And he had no idea which of the two had a higher priority.

But first things first. He needed 468 and an appropriate lab before he could think of anything else that might lie ahead of him.

He closed his eyes for just a moment and rubbed the increasing tiredness out of them, when he heard it.

_Beep!_

He immediately was wide awake again as he checked his e-mails. A smile appeared on his face when he found the long awaited e-mail in his inbox.

_Finally!_

But when he read it, the smile faded again and was replaced by a deep frown.

Okay, this was going to be a bit harder than he had thought. Well, to be honest, _a lot_ harder.

* * *

When they were all gathered in the kitchen the next morning – well, except for Master Splinter who preferred to drink his morning tea in his room and then spent the morning meditating – Donnie thought it was time he filled his family in on the details.

Okay, his family and Casey. The young man was still here, and by what Raph had told Donnie, he wouldn't leave before he hadn't gotten all the supplies he needed and had sold all of his groceries. From what Donnie knew only a bit of groceries were left, but whatever Casey needed, he had failed to trade yet. So he could be around for some time still.

Donnie didn't really care. It was just…unusual to have Casey around for such a long time. While he and his brothers had lived with April for a few weeks when she had had to hide from the Kraang and Shredder, Casey had never been around for more than a day in a row.

But now he stayed at the lair permanently, only leaving for his trading walks at which most of the time Raph and sometimes even Leo and Mikey accompanied him, and he would stay at the lair for the duration of his visit. And bumping into Casey several times a day just was something Donnie had to get used to. It wasn't something he had to get used to _again_ like it was with his family, it was something he had to get used to _completely_ because he had never experienced that before.

Things sure were a lot easier between him and Casey since they had buried the hatchet, but Donnie knew for sure that they would never become best friends – they were way too different for that –, but friends. And for him that was sufficient.

"Man, you look tired," Mikey announced when he set eyes on Donatello.

"Mikey, I had the night shift, what did you expect?" the purple-masked turtle gave back. "That I came in here, being as fresh as a daisy?"

"Hmmmmmm…" Mikey twisted his mouth and furrowed his brow, brooding over the said for a moment, before he turned to his brother with a wink. "You have a point."

Donnie just rolled his eyes in return.

"Just help yourself with some breakfast and then catch up on some sleep," Leo told his brother.

Donnie nodded. "But I need to tell you something first."

Immediately, five pairs of eyes turned into his direction.

"I received a message from my friend from New Delhi tonight," Donnie announced. "The shipment he had promised me is going to arrive tomorrow." He got the map of New York he had had tucked under his belt out and unfolded it on the kitchen table. "And they are going to drop it in this area here."

He encircled the said area with his index fingers, and he could literally hear how these five pairs of eyes widened in surprise.

"But that's pretty close to Central Park!" Leo pointed out. "Or even Central Park if we have tough luck with the wind conditions!"

"You gotta be kidding, bro!" Mikey concurred.

"Yeah, why don't they drop the shipment somewhere easier to salvage from? Like Rahzar's lair!" Raph added angrily.

"I'm sorry, guys," Donnie said, "but he has only been able to get the shipment onboard this test flight, and it would raise too many questions if they open the hatchway sooner."

"Wait, why would they open it anyway?" Leo asked.

"They…are…sort of testing a new herbicide that maybe would work for mutated plants as well," Donnie admitted hesitantly.

"Wait, wait," Leo said. "Just to get this straight: We not only have to go to Central Park, we also have to face a cloud of herbicide?"

"No," Donnie gave back, and Leo sighed in relief. "We only would have to go to Central Park if we have tough luck with the wind conditions."

"And what exactly makes this any easier?!" Leo gave back hectically.

"Nothing," Donnie said with a shrug. "But it's important to be accurate."

The reply to this were frustrated grunts by all three of his brothers – something they always did when Donnie insisted on being accurate. And Donnie again had to blink back tears when he realized that this was one of the things that hadn't changed.

* * *

The next morning when they were all gathering their stuff and prepare themselves for their mission, Leo watched for an opportunity to talk to Donatello in private. And when Donnie went for the dojo to fetch his bo, Leo seized his chance and followed him.

He was pretty sure that his brother must have sensed him when he had entered the dojo, but Donnie didn't even turn around. He just kept standing there with his back to Leo and looked like he was examining his bo closely.

"You haven't come to talk me out of this, have you, Leo?" he said, his back still to Leo.

Leo froze for a second, blinking his eyes. While Donnie sure had lost quite a bit of his old form, when it came to his physical abilities in fighting, his mental abilities had increased indeed. Leo could only wonder why, but maybe it had something to do with the fact that his brother had been on his own all this time, not sure who was friend and who was foe, and thus had had to develop his senses and his mental abilities to be able to estimate someone right away, to know if it was worth a fight or if he even stood a chance in a fight or taking flight was the better alternative. For a second there, Leo really thought that maybe he should consider fending for himself for a few months, just to gain the same abilities as his brother had – but of course, without letting his physical training slide. But he quickly shook this thought off. His family needed him.

"Just think of it, Donnie," he talked to his brother who still refused to turn around. "You say yourself that your fighting skills have dropped and your ninjutsu has gotten rusty. Heck, you even refuse to spar with any of us, just because you think you might embarrass yourself. It would be safer if you stayed here. The others and I can salvage this shipment."

Donnie shook his head.

"Donnie, please!"

"Leo, I have to do this," Donnie gave back. "I can't let you do all the work. I have to go as well. I _need_ to go!"

"But Donnie…" Leo was stopped by a quick swing of Donnie's bo that swept his feet away from under him, and Leo landed on his back with a thump.

"Ouch!" he protested. "That wasn't fair! You took me by surprise."

"Is that so?" Donnie gave back with a smirk. He was finally facing Leo, casually resting on his bo. "For someone who is as skilled in ninjutsu as you are, don't you think it should be a bit harder for someone as rusty as me to be able to do that?"

Leo just grunted. "I see your point."

"Good." Donnie held out his hand and helped his brother to his feet. "So am I allowed to come?"

Leo sighed. "You are," he gave in. "But you'll have to team up with Raph, and whatever happens, you stay close to him, understood?"

Donnie gave slight nod. "Understood."

* * *

Leonardo, Michelangelo, Donatello, and Raphael stood on a rooftop. All four of them were wearing face masks.

"You all know the plan," Leo told his brothers, his voice muffled a bit by his face mask. "Mikey, you and I build a team, as do Raph and Donnie. And whatever happens, stay close to your partner. We don't know what we have to face in there." He tilted his head into the direction of Central Park. "So be careful! And whatever happens, we stay within earshot. No-one, I repeat: _no-one_ should be on his own in there. Is that clear?"

The three other ninja turtles nodded in response.

"Good," Leo said and lifted his eyes to the sky. "'Cause here they come."

And that moment the air was filled by the roaring of an airplane, and then the plane flew over them, and seconds later its hatchway was opened, and they could see a big, orange package fall down. They all followed it with their eyes, but then another package was dropped, a smoking package, and a second one, and a third, and pretty soon the air over Central Park was filled with smoke.

"Okay, I guess our shipment just missed Central Park, but the outskirts aren't hazard-free, so be careful," Leo told his brothers. "Let's move!"

And with that, they set off.

Donnie sure had problems to stay close to Raph, when they separated from Leo and Mikey to search the area for the shipment, but Raph made sure he didn't fall behind.

The outskirts from Central Park were deserted. People avoided Central Park and had left their houses abandoned when they seemed to be too close to the park. This had led to the nature to win back parts of the area around the park, although it was a mutated nature here. But it wasn't as dangerous as Central Park itself. The plants here couldn't move their tendrils like some plants inside Central Park could – at least that was what they had been told was one of the strange things that happened in Central Park, not to mention the strange mutants that should roam in there.

But Donnie shoved these thoughts aside. He needed to concentrate on the task ahead. He searched his surroundings for a sign of the package.

"I think I got it!" Raph suddenly called out and pointed ahead.

Donnie looked into the direction, and caught a glimpse of orange.

"I guess you're right," he gave back, and with that they both ran over to the place where they presumed their package was.

And when Donnie set eyes on what really was their package, he let out a sigh of relief.

"Let's get it!" he said to Raph. "And then we better leave."

Raph answered with a nod and ran over to the package, followed by Donnie. It was so big that it would need at least two turtles to heave it. Raph lifted it on one side, and Donnie took care of the other side.

"Hey, Leo!" Raph called out as loud as he could. "We found it! Let's go!"

"That's great!" he suddenly heard Leo's rushed voice behind him. "Hurry!"

And with that he ran over to help his brothers with the shipment, and he was soon followed by Mikey.

"What's going on?" Donnie asked as they started to get their shipment out of the area.

"Let's just say the herbicide disturbed a few of the inhabitants of Central Park," Leo explained.

"Yeah," Mikey approved. "A few of the _moving_ ones!"

But then there was a tumult behind them, and the brothers' eyes widened in shock.

"Quick!" Leo called out, and they started running as fast as they could with their load. But then they were passed by small animals, rats and mice.

"But that's only small animals," Donnie said.

"Yeah, and we better be out of here before their big brothers show up!" Leo called out.

But then they could feel it. It was as if the ground was shaking beneath their feet.

"Uh-oh!" Mikey called out. "Big brother's coming up!"

Leo hectically searched their surroundings, desperately looking for a place to hide, until he finally set eyes on an apartment building that looked like it wouldn't collapse any minute, which actually was unusual for this area.

"Over there!" he told his brothers, and they did their best to reach the building quickly. Once inside, they put down their load, and Raph grabbed the old front door to block the entrance. Then they planted themselves around the package in the middle of the entry area.

Donnie couldn't prevent his hands from shaking as he clutched his bo. He could feel the tension from his brothers, and although he tried his best to keep his breath calm, he couldn't help that it accelerated.

And then they could all hear it, a roar, a nearby roar. The shaking of Donnie's hands got even heavier now, and he clutched his bo so hard that his knuckles turned white. The floor beneath their feet was shaking even more now, and suddenly the sunlight that fell inside from a window was blocked out, and Donnie held his breath. But whatever was out there, didn't stop for long, it was too eager to get away from the poisoned air.

Donnie let out a sigh of relief when he heard departing footsteps.

"We better wait until we're sure the coast is clear," Leo told his brothers and they all nodded in response.

But then there was a crumbling noise, and something hit Mikey's head. The orange-masked turtle lifted his head, and his eyes widened in shock.

"Or we better get out of here right now!" he called out. "The building's coming down!"

His brothers looked up as well and gasped.

"Move it!" Leo called out, and he, Donnie, and Mikey lifted the package again, while Raph was unblocking the doorway, and the moment he did so, they were met by yellow fog, light, though, but still there.

"Wait, move – could you please make up your mind, Leo?" the turtle in red asked. "This is confusing!"

"Good that you haven't lost your sense of humor!" Leo gave back. "Hope you haven't lost your strength either!"

Raph just smirked as he joined his brothers. They were moving so fast, Donnie had no chance to look out where he was setting his feet, and that was when he missed the piece of ceiling rolling in front of him and he tripped, letting go of their load in the course of this, and fell down. He wanted to call out for his brothers who had kept on moving and probably had missed what had happened. But suddenly something hit his head, and everything went dark around him.

* * *

His head was aching like crazy, and he wondered if someone got the number of the bus that had hit him. He could feel something warm run down his arms, and he was afraid it could be blood, but then he could feel something soft and warm, touch his upper arm and stroke it down to his hand, and he couldn't help, but enjoy the feeling. It made the aching of his body a bit less painful.

He gave a little sigh which made whoever was there with him gasp silently.

"Donnie?" a familiar voice asked softly.

"In person," he mumbled as he did his best to open his eyes which finally worked at his third attempt. He moved his head to face his tender carer.

"You got the number of that bus, April?" he asked, forcing himself to smirk, which actually hurt a lot, but he didn't care.

April let out a sigh of relief, closing her eyes while doing so. She then put the piece of cloth she had used to wash his skin back into the bowl with warm water.

Donnie followed her movements with his eyes, but then struggled to sit up.

"No!" April said quickly and pushed him back on the mattress. "You maybe have brain concussion. Seriously, Donnie, you've been nearly buried under an entire building. If Raph hadn't gotten you out of there before they building came down, it would have been a lot worse than just a bar hitting your head. Which is worse enough."

"Where is Raph?" Donnie asked. "And the others?"

"Having a shower," April declared. "Getting the herbicide off their skin."

Donnie just nodded. "I see."

So that had been the reason why she had washed his skin, he thought, to get the herbicide off. And for a moment he had felt like April was back to her old self again, treating him like a friend, caring for him, but as she stood up now, he could literally see, how she built up her invisible walls around her again.

"I am getting the others," she announced and left Donnie's room.

Only moments later Donnie could hear quick footsteps approaching, and Mikey darted inside his room.

"Donnie!" he called out, flinging his arms around his brothers neck, and Donnie moaned in pain which made Mikey immediately let go of him again.

"Sorry, bro!" he said with a sheepish grin.

"It's okay," Donnie gave back with a smile.

Leo entered the room next, followed by Raph. The Turtles' leader walked over to Donnie and placed a hand on his shoulder.

"You really got us worried this time, Donnie," he said with a smile.

"Sorry," was the reply.

Raph just looked at Donnie, his brow furrowed, his arms crossed over his chest, an angry look on his face.

"Good, you're awake again," he finally said grumpily, turned around and left the room again.

Donnie looked after him with a frown.

_Speaking of invisible walls…_

He turned to Leo with questioning eyes.

"He…just was worried," Leo gave back. "You know Raph."

"Yeah, he isn't an emotional kind of guy," Mikey added with a shrug. "He's just a … uhm … Raph."

Donnie nodded. But that didn't make him feel any better.


End file.
